Eradicating an Insect Infestation

A load of insect-infested reclaimed wood may have contaminated a whole operation. What to do? April 20, 2011

Our specialty is reclaimed lumber, so we obviously deal with a lot of questionable material. Mostly we have used northwest softwoods, so we don't have too many problems with pests. I recently acquired several loads of hardwoods, and it is terribly infected with pests. The wood is mostly oak, with some maple and other species. It is all old wood and it has tiny bugs crawling all over it when one opens up the units. I think these are powder post beetles. I've read here on them and elsewhere as much as I can.

I have a converted shipping container that I can get very hot (200 plus degrees) with a wood heater if I want. I've heard all over the board on the temperature and time it takes to kill bugs from 130-180 degrees and from 3-24 hours. I know it is tough to say, but I want to err on the conservative side. Is this always the temperature of the wood rather than the air temperature in the box? I don't have a means to measure that. If the wood is stickered is there any kind of rule of thumb to know how long it takes a 70 degree board to get up to the air temperature? How can I be sure this also kills the larvae and eggs?

In my hot box I'm having a bit of a problem with consistent air temperature. I can have a major differential between ceiling temperature and floor - as much as 20-60 degrees. I've been researching kiln fans, and I don't want to make that $1000 plus investment right now. Our kiln hot box is more for killing bugs than drying wood. Our wood is already 8% with just air drying, so that isn't too hard to deal with.

Before I heated a batch of wood recently I brought some into the shop to measure and cut into manageable lengths. I'm blaming that as now I see these critters crawling all over the floor. They are about the size of a fat pencil head. I keep trying different insecticides on the floor, and it doesn't seem to stop them. They just jump when sprayed. I've treated the whole place with several different bug sprays, but they continue to crawl around. This is my big question. I'm worried my whole operation is compromised. I'm trying to run everything through the hot box even if I don't use it right away, but it seems that these bugs are pretty nomadic. I also have noticed some ants and earwigs in this stuff. Are the earwigs wood destroyers?

I've seen the different concentrated treatment products out there like Boracare, but I don't really want to unstack dozens of units to spray and treat each layer. Plus that would be outrageously expensive. Is there any way to just treat around and on the unit without busting it open to prevent the spread, and then also hope that a good sauna in the hot box brought the grim reaper?

Forum Responses
(Sawing and Drying Forum)
From Gene Wengert, forum technical advisor:
1. Get the insect identified. Your county extension office can do that.

2. Insects in wood are not affected by insecticides put on the floor or sprayed on the lumber's surface (but you might be bothered by such applications). Your extension agent can provide guidance.

3. 133 F wood temperature is the number. You can easily and inexpensively measure temperature with devices. Are you in Oregon? If so, contact OSU Forest Products Lab for on-the-ground help. (In Canada, UBC.) Other states will likely have similar help from the state university.

4. These insects live in dust as well as lumber, so you may be faced with a real thorough office cleaning job. Once lumber has been heat-treated, then you must keep this lumber away from all untreated hardwood lumber (4x4s, stickers, etc.), dust, etc so that it does not get re-infected and then in six months, they appear again in the customer's home or office.

In the PNW, I have heard that there is a PPB brought from Asia that infects softwoods too. Be alert for this.

From contributor B:
Wow, sounds like you have a real mess on your hands. I hope you didn't pay anything for it. I live in Oregon, and have heard numerous times that our local oak is a haven for ppb's; some people refuse to use it for that reason. I have seen biting ants in black walnut sapwood, and earwigs and centipedes in the bark of the big leaf maple that grows around here; but both only in older wood, not freshly cut. Often I see tiny holes in the burls of the maple, but haven't seen the bugs yet; I burn it. I also see tiny holes in our Douglas fir, I burn that too.

I haven't had a bug problem yet, but I keep the fire going; no time for that. Ppg's will burrow out of the wood and deposit their eggs on the surface, the larvae then burrowing back in when hatched leaving holes so small they just about cannot be seen; if you have them crawling all over, it's more than any easy answer is going to help. There are bug sprays that state they kill the bugs, I use one type that is a powder I mix and liberally spray on; I cannot say how well it works as I use it right after I slice the wood, and I burn the wood I worry about, but as I said earlier I don't yet have a problem.

There are liabilities with using them, look into them before doing so if you choose to; but I think your problem is way beyond a spray. I would suggest baking the little boogers; a good 140 degrees, and for long enough to sink the heat all the way in to the core of the wood. You can purchase a heat detection tool at most hardware stores. The oak will suffer, and may even completely crack out; but it's useless as it is, right? I wish you the best of luck. If you are able to save the wood, please write back with how you did it.

From Gene Wengert, forum technical advisor:
A spray will not work for PPB’s that are already in the wood. The spray chemicals do not go more than 1/100" deep, so they will not reach existing insects. They may affect the larva, but it may be several months before the larva appear and by then the insecticide may have lost most of its strength. Hence, a green spray treatment will probably do no good. The exception would be borates.

From contributor B:
I agree Doc; the spray I use is a borate product, and I don't rely on it to eradicate all pests, nor would I advertise it to; it's just a step I use. I collect older woods and peoples' pet trees for rescue from the fireplace, and some of what I get is less than wonderful. I keep the best and burn the rest. I only spray wood that is well dead, say from logs that have been laying for a year or two, and I saturate them a few hours after I slice them. I figure on keeping the wood for a couple of years, so I keep an eye on it.

This process is one I use at the suggestion of a guy named Jack DeAngelis who I met at a local wood guild meeting; at that time he had a Ph.D. in entomology and was working thru OSU in bug controls. I'm hoping (well, relying really) on it working as suggested by him as well as the statement from borate solutions' manufacturer. Of course, I'm not saying you are incorrect, just that I am working with seemingly differing information; I guess I'll find out how it works for me. Nothing, though, is as important as cleanliness, and your suggestion of cleaning (and keeping) the system clean is certainly of the top priority.

From Gene Wengert, forum technical advisor:
The borate will stop new infestations fairly well, as you describe it, but it will not have much effect on existing infestations as the borate cannot penetrate into the wood deeply (from the side grain) and stop all the insect's activity, as the insect does not encounter the borate on or near the surface in most cases. For full treatment, the wood needs to be soaked until it is saturated all the way through.

From the original questioner:
Thanks for all the responses. I'm slowly been seeing less bug activity around the place. I've had everything cleaned up (much easier said than done). There is sawdust stuck in nooks and crannies that just may be there forever. I've sprayed several insect treatment products on the floor; I don't think these do much to these bugs. I also set off several foggers on two different occasions inside the building. These seemed to help a little. It is now rare to see the bugs. I've also cycled all my wood through the hot box. I have a new policy to cook any wood that is going into a new project even if it is dry and was previously baked. These things can cause extreme paranoia.

Has anybody baked completed/ glued-up wood pieces? What temperature can most cross link PVA glues tolerate? How long can PPB live outside of the wood in the open air? If you see them crawling around, how soon will they mate, lay eggs, or try to bore back into a new home?

From contributor B:
It's my understanding they will lay eggs on the surface of wood, then either crawl back in their hole or fly away. Once the larvae leave said egg they bore their way into the wood leaving the tiniest of holes to turn into a brand new bug that will bore its way out, repeating the cycle. I don't know if they mate. The statement for the bug sprays I use is that it will kill the bugs when they eat it, so the hope is as they bore in or out, they will eat some of it; it is also supposed to kill the eggs if they are laid there.